Behavioral response of unmated female Plodia interpunctella Hübner (Lepidoptera: Pyralidae) to synthetic sex pheromone lure

Authors: Gerken, Alison; Dryer, Danielle; ABTS, SHELBY - Kansas State University; Campbell, James - Jim

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2022
Publication Date: 11/5/2022
Citation: Gerken, A.R., Dryer, D.L., Abts, S.R., Campbell, J.F. 2022. Behavioral response of unmated female Plodia interpunctella Hübner (Lepidoptera: Pyralidae) to synthetic sex pheromone lure. Environmental Entomology. 51(6):1200-1209. https://doi.org/10.1093/ee/nvac087.
DOI: https://doi.org/10.1093/ee/nvac087

Interpretive Summary: For many insect pest species, females release a pheromone to attract males. Mating disruption is a pest management technique that uses application of high concentrations of pheromones to disrupt males locating females which can prevent or delay mating and subsequently reduce the pest population. Typically, mating disruption is targeting male behavior and this has been the focus of research related to behavioral responses to pheromone. However, females may also be able to detect the pheromone and may be affected by mating disruption treatments in ways that could potentially increase or decrease treatment efficacy. The Indianmeal moth, Plodia interpunctella, is a common pest of stored products, and mating disruption is a method used to suppress populations. However, how females respond behaviorally to high concentrations of pheromone has not been evaluated. We compared two different populations of Indianmeal moth for the females’ response to pheromone lures by quantifying time spent calling (emission of pheromone to attract males), time spent walking, and time spent cleaning their antennae (which can be associated with detection of chemical cues). We also quantified overall movement behaviors, including time spent immobile and time spent in quick bursts of movement. The presence of pheromone had a significant impact on the behavior of unmated females, with an overall decrease in quick movements and time spent walking when the pheromone lure is present. The two strains showed differing responses in calling behavior, with one strain increasing their calling behavior and the other decreasing calling when pheromone is present. These results show that females are detecting pheromone within the environment and are altering their behaviors. Overall decreases in movement by females should increase effectiveness of mating disruption, as females are less likely to encounter males by chance if they are not moving as much. Increasing calling could result in higher mating success, as females attempt to outcompete the pheromone lure within the system. These findings suggest that further research is warranted to determine the level of impact changes in female behavior will have on mating disruption treatment success and how these behavioral responses might be exploited for greater mating disruption success.

Technical Abstract: Indian meal moth, Plodia interpunctella Hübner, is an important pest of stored products in food facilities such as processing plants, warehouses and retail stores. Mating disruption, which uses synthetic pheromone to delay or prevent mating, is a relatively new management tactic for this pest but is becoming widely adopted. However, little is known about the mechanisms behind its efficacy, including how artificial pheromone might impact female behavior. Here we assay behavioral responses of two strains of unmated female P. interpunctella during exposure to pheromone. Results show one strain increased the duration of calling behavior while the other decreased calling when exposed to pheromone lures. Time walking decreased, and time cleaning increased for both strains when exposed to pheromone. Time of first walking behavior was also delayed for one strain when exposed to pheromone. Females of both strains were less mobile when exposed to pheromone. These results show autodetection of pheromone by females, but also indicate that strains may vary in behavioral responses. Differing patterns of calling behavior between strains could be driven by either strain-specific genetic differences or laboratory induced effects. Decreasing calling behavior and overall movement during exposure to pheromone could enhance the effectiveness of a mating disruption program. However, increased calling by females in the presence of pheromone may be a competitive response and could increase mating success under certain scenarios. These findings suggest that artificial pheromone associated with monitoring and mating disruption programs has impacts on female behavior and warrants further study to determine the overall impacts on program effectiveness.